Different gas for stouts?

A buddy of mine (who used to work for an air gas supplier) said that if I'm going to have stouts I'm going to need to have a "beer gas" setup...that is, CO2 with a mixture of nitrogen.

Is this true? I knew I'd need something special for, say, a Guinness clone...but is this true of really any stout?

If so, what's going to happen if I just go with CO2 for the time being?

Only if you want to. I don't think it's a real necessity for a HBer. We're kind of flexible that way.

It will be fine with just CO2 but a beer gas and stout faucet setup is awesome for serving really creamy beers with that Guinness look and mouth feel.

I personally like dry stouts and low-aroma/flavor-hopped bitters on nitro, but it's not a requirement. If you use beer gas you'll want a stout tap to get the benefit from it. The gas mix itself doesn't do anything to the beer, it's just so you can use higher pressure without overcarbonating the beer. The high pressure (I use 26 to 28 PSI) is needed for the stout tap to work correctly.

I have a sort of guinness clone on tap right now with Co2 and it works just fine. I know it probably would be a denser head with beer gas but I'm not that worried about how it looks.